This invention relates to a heavy duty vehicle suspension system, and more particularly, the invention relates to a trailing arm structure and method for manufacturing same.
Various suspension systems have been employed for heavy duty vehicle applications. For example, trailing arm suspensions have been used in motor homes in which is a forward portion of a pair of opposing trailing arms are pivotally attached to the frame. The wheel ends are supported on the trailing arms, and suspension components are arranged between the trailing arm and the frame.
Typically trailing arms are designed to withstand the bending forces of the suspension components acting on the trailing arm and inputs received through the wheel ends from the road way. The trailing arms may be subjected to significant bending and torsional inputs, and as a result, must be designed with sufficient structural rigidity. Some trailing arms are rather large cast components having significant weight. Other trailing arms have been proposed such as side plates that are bolted together. An adapter plate is supported between the side plates to support the suspension components. However, such trailing arms typically do not have sufficient rigidity for the intended application. Moreover, these trailing arms have required the use of numerous bushings and fasteners. Therefore, what is needed is a trailing arm with reduced weight and of sufficient structural rigidity to withstand bending inputs while minimizing torsional inputs acting on the trailing arm.
The present invention provides a trailing arm for a vehicle suspension including a forward portion. The forward portion extends longitudinally to a rearward portion with the trailing arm having at least a portion with an open bottom. The trailing arm preferably has a generally U-shaped cross-section over a substantial portion of its length. A bushing assembly is secured to the forward portion defining a first pivotal connection by which the trailing arm is secured to the frame. An air spring support plate is secured to the rearward portion opposite the open bottom. Preferably, the trailing arm tapers inwardly from the rearward portion to the forward portion to provide increased structural rigidity in the area of the trailing arm that supports the axle and other suspension components. The trailing arm is formed of a sheet of metal to provide the generally U-shaped cross-section. The bushing assembly is welded to one end portion of trailing arm to define the first pivotal connection, and an axle attachment member is welded to another portion of the trailing arm. Brackets and plates for supporting suspension components such as air springs, an anti-roll bar, and shock absorbers may be welded to the trailing arm. The main portion of the trailing arm does not have any welds.
Accordingly, the above invention provides a trailing arm with reduced weight and of sufficient structural rigidity to withstand bending inputs while minimizing torsional inputs acting on the trailing arm.